1865.] CARPENTER— STRUCTURE OF EOZOON. Ill 



presented by specimens from the Calumet, which are regularly 

 laminated like those of Burgess, and tubulous like those of Gren- 

 ville. It is possible that in the Burgess specimens tubuli originally 

 present have been obliterated ; and in organisms of this grade, 

 more or less altered by the processes of fossilization, large series 

 of specimens should be compared before attempting to establish 

 specific distinctions. 



Some additional specimens, from a block consisting principally of 

 serpentine, differ from the ordinary Grenville specimens in the 

 more highly crystalline character of the calc-spar and ser- 

 pentine, in the development of certain minute dendritic crys- 

 tallizations, and in the apparent compression and distortion of the 

 fossils. These appearances I regard as due to the mode of 

 preservation, rather than to any original differences ; certain 

 portions less altered than the others presenting the ordinary typical 

 characters. 



Two slices of limestone from the British Islands, and supposed 

 to be Laurentian, have been compared with the Canadian lime- 

 stones above noticed. One is a serpentine-marble from Tyree. It 

 appears to be fragmental like some of the Laurentian limestones 

 of Canada, and may contain fragments of Eozoou. The other is 

 from Ireland,* and presents what I regard as traces of organic 

 structure, but not, in so far as can be made out, of the character 

 of Eozoon. Both of these limestones deserve careful microscopic 

 examination. 



NOTES ON THE STRUCTURE AND AFFINITIES OF 

 EOZOON CANADENSE. 



By W. B. Carpenter, M.D., F.R.S., F.G.S. 

 [In a Letter to Sir William E. Logan, LL.D., P.R.S., F.G.S.] 



The careful examination which I have made — in accordance 

 with the request you were good enough to convey to me from Dr. 

 Dawson, and to second on your own part — into the structure of 



[* Given by mistake as " Iona" in the Journal of the Geological Society. 

 It is a specimen of Connemara marble from the collection of Dr. Hunt, 

 who supposed it to be Laurentian. See note on page 93, and for 

 further observations on this marble see below, p. 128. J 



